I used fresh sterile potting mix, pushed 1/8" depressions in cells, carefully laid a seed in each depression, did not cover the seeds, put some tepid water into the flat until I barely felt moisture at the top a day later, left the flat in the kitchen at 70 degrees F in indirect sunlight.

Most of the seeds are growing mold and none have germinated after 2 weeks. I put a cover on the flat to keep the cats from pawing at the soil. Was that the problem? The soil wasn't so damp as to cause condensation inside the cover.

I did a bunch of research on impatiens online and it said they germinate best at 75f ( That is soil temp not room temp.) Mine was at that temp for 5days while they germinated.So if your flat with the dome becomes too hot that could make them mold. I sure hope this is not to confusing. If all else fails you could germinate them really fast by the baggie method (wet paper towel in a plastic baggie set on top of the fridge or freezer.
I had my flat with the dome covering it and it had water droplets all along the walls.I read that lots of humid air is perfect for germinating, just not good after germination. So humidity is actually really good while germinating. I also put a little digital meat thermometer in a hole in the middle of the dome that let me know the temp of the soil constantly.
Don't give up I am sure it seems hopeless but I am sure there is something that just needs minimal adjusting. Hope this helps :)
I would say you need more humidity, and the dome should stay in place with a soil temp consistant between 70f-75f. I pre moisten the soil with 3 parts soil to a little less than 1 part water then i mix it all up and fill the cells. Then I placed 2 impatiens seeds right on top and then misted them with a water sprayer then I put them in my spare bedroom under two fluorescent tubes for 5 days at 75f soil temp (with dome on top. I kept the light on day and night to keep the temp the same. It worked! I did not really know what to go on except three things lots of humidity,surfaced sown with light, and a soil temp of 75f
I would give that a try, I sure hope it works out for you.

What kind of impatien are you trying to grow?

This is the information I got on germinating/growing impatiens...

Seed size varies drastically by color from 35,000 to 90,000 seeds per oz/28 g
Soil temp. must be maintained @ 72- 74°F /22 - 24°C at all times. Seed germinates irregularly and slowly @ 60% - 80% in 20 days. Intense direct or artificial light, which is high in the "red" part of the spectrum of light - will limit germination of some colors. We suggest that you start Impatiens on the north side of the greenhouse or shade, flats lightly with blue plastic or cheese cloth. After and during germination, remove plastic or glass, during the heat of the day. Keep medium moist to the touch, but not saturated. Shade seedlings at all times. Never check the plant growth. Using soil that has a neutral pH reading, transplant seedlings at the same depth as they were in the seedling flat - this reduces stem rot at the base of the plant. Grow plants at 60°F/16°C, keep them on the dry side and do not fertilize. Keep transplants well ventilated, and out of cold drafts - which weaken the plants. Allow the plants to cycle through wet/dry periods. Excessive moisture will result in tall, lush growth. Treat with Captan every 10 days to control damping off.

IMPORTANT: New Guinea Impatiens soil temp. must be maintained at 77 - 79°F/25 - 26°C for seed to germinate. New Guinea types should be lightly covered with coarse vermiculite at sowing.

All this being said, I grow mine in my livingroom under
lights - NO heat, just lights. I have a friend who
germinates at 68 degrees and he has excellent luck... We
both use domes - he takes his off right after germination,
I leave mine on a little longer...

Pics:
I found these troths a few years ago - I love them. Not
been able to find them since. (these are germinating begonias not imps):

Partial set up - lights...

germinating imps:




After germination:

These are begonias, BUT I treat the impatiens the same -
under domes...

Right after transplating:

after transplanting (few weeks later):

This looks pathetic, but: (transplanting into bags):

the bags end up looking like this:

I've digressed:

I think hummer above is right with the moisture... I have
lots of condensation - even though I'm growing them at a cooler 65-70 degrees.

I saved seed from last year - if you want some free seed - ?

Re-reading my post, I note I left out some info. While the flat was not in direct sunlight, it IS 14" below a single fluorescent bulb which I left on during the day.

Also, I realized later that I had added a small amount of sifted compost into my starter soil (I mix my own from bulk sphagnum moss, sand, vermiculite, and compost). It works great for all my other seeds so I didn't think about the compost.

The seeds are 3 years old, because I haven't ordered from Parks since 2006, and I suspect that may be the real problem. But I keep all my seeds in capped vials that are stored in the refrigerator, so I would think that a few should have germinated.

It definitely IS mold. 0% germination.

The pack instructions said best germination "about 72 degrees", but did not say how many days it should take.

I think I'm going to assume it was their age...

Don't let this stop you from doing imps again. They're very versitile and easy once you get the hang of it.

Oh, and lower your lights. I keep might right over the dome...

On occassion, I also have had very low germination with impatiens (especially certain New Guinea varieties). A few years ago, I ordered multiple packs of NG Java Series Impatiens from Parks and had almost no germination.

Provided you followed the germinating instructions, most retailers and online seed sources will refund your money in the event of very poor germination.

Regards,

Ron

Nancy

I order my impatiens seed from stokes I like the tempo series because it has good sized blooms and it is the earliest to flower--250 seeds for a little over $7.